The present invention relates to a one-rotation clutch for selectively transmitting a drive force through a coil spring and interrupting the transmission and, more particularly, to one which is suitable for effecting intermittent motions such as sheet feeding and sheet cutting motions which are required for an electrophotographic copier or a facsimile apparatus.
One-rotation clutches are installed in electrophotographic copiers, facsimile apparatuses and various other apparatuses in order to transmit rotational drive forces from motors or like drive sources to sheet transport mechanisms, sheet cutting mechanisms and the like associated therewith. One-rotation clutch of the type described is interposed between a sprocket rotatable in a predetermined direction through a chain, which transmits a rotational drive force from a motor, and a drive shaft on which a driven member of a desired mechanism is rigidly mounted. In this construction, when the driven member or the drive shaft is rotated by hand in a predetermined direction, the manual effort also causes the drive source, or motor, into rotation by way of the sprocket and chain. Therefore, a substantial load exerted by the drive source has to be overcome when it is desired to manually rotate the driven member or the drive shaft, such as when a registration roller or a sheet feed roller should be rotated in a sheet feed direction to remove a jammed sheet, or when a rotary cutting edge of a cutter should be rotated to manually cut a sheet.
Some approaches may be contemplated to solve the problem discussed above as exemplified by uncoupling a clutch by means of a release lever, using an electromagnetic clutch in addition to one-rotation clutch in order to disconnect the drive source load therewith, and supplying an electrical uncoupling signal, which is applicable to a case wherein only an electromagnetic clutch is employed for effecting one rotation. However, none of these approaches can be implemented without an intricate construction which would deteriorate the reliability of the whole apparatus and increase the costs.